The goal of this proposed project is to describe and explore reasons for the rising incidence of treated end-stage renal disease (t-ESRD) in the United States and to predict future incidence trends. New cases of t- ESRD have been increasing at an average annual rate of 7 to 8%. Although the incidence rate was expected to plateau as all eligible patient groups were accommodated under the Medicare-sponsored ESRD program, growth has actually continued at a steady rate. The number of prevalent cases has grown in concert. The continued growth in ESRD cases consumes vast personal and societal resources. Investigation of this growing public health problem is needed to elucidate reasons and possible remedies for the problem. USRDS files will be used to test specific hypotheses about the rising incidence of t-ESRD over the period from 1980 to 1990. The hypothesis that t-ESRD is growing due to increasing referral and acceptance of elderly patients who, as a group, were less likely to receive dialysis treatment in the past, will be tested for exclusivity by comparing growth rates for different age groups. Growth in younger age groups would suggest that other factor contribute to the growth of t-ESRD. The large USRDS database will allow the question to be asked for specific race and diagnosis groups. The hypothesis that improved access to ESRD treatment is a driving factor behind growth will be tested by comparing growth rates in counties with and without a dialysis unit during the study period. A comparable rate of growth in both types of counties would suggest that limited access has not impeded growth and that improved access is not a major factor driving growth. The hypothesis that growth in dialysis facilities spurs growth through enrollment of patients sooner than necessary will be indirectly tested by comparing the rate of t-ESRD growth before and after opening of a dialysis unit in counties that previously lacked any dialysis facilities. Accelerated growth after opening of a new unit would suggest that supply is driving demand whereas balanced or increasing demand. The hypothesis that t-ESRD growth is related to socioeconomic status will be tested by comparing growth in counties classified as to race-specific per-capita county income as revealed in the Bureau of Health Professions Area Resource File. Previous studies indicate that incidence falls with rising SES but the growth rate has not been analyzed in relation to SES. Failure of the above process-related hypotheses to largely explain the rapid growth rate of t-ESRD would raise the possibility that the underlying renal diseases that cause ESRD are increasing. County mapping analysis of t-ESRD growth rates will be done to evaluate areas of extremely high or low growth that may illuminate the underlying reasons for growth. Finally, the information learned about t-ESRD growth will be incorporated into a descriptive/mechanistic model for prediction of future trends. This study should provide important new information to guide future efforts at studying, preventing, and predicting growth in new cases of t-ESRD.